Looking for a usable solution for Z-pass aliasing
Use this shader as an override for all your materials in Render layers and render a perfect Z-depth pass that is pixel-perfect anti-aliased like your final render:





It shades the geometry based on distance from camera and renders fast (only 1 emission shader, you can omit the black emission).

It is basically similar to the mist past, but let's you do more magic for example with transparency if you need.